In general automatic phonographs of the coin operated types commonly referred to as "juke boxes", include a record holding magazine moveable through a scanning cycle for the purpose of making selections to be played. The magazine operates in conjunction with a record transfer means which importantly serves to remove the selected records from the magazine and transfer the same to and from a playing position atop a rotatably driven turn table. Typically rotary motion of the magazine has been found to be preferable to provide maximum storage capacity and minimum space.
Magazines and record transfer means of the order above referred to are disclosed in U.S. Pat. Nos. 2,804,307 issued Aug. 27, 1957 and 3,030,116 issued Apr. 17, 1962.
Recent developments in the record art have resulted in the so called compact disc or C.D. record which while generally smaller than a familiar long play record has a greater playing capacity with improved fidelity and lighter weight. Such compact disc records employ laser pick up responsive to reflected light energy thereby eliminating the familiar tone arm and needle pick up and its attendant drive mechanism. With laser pick up, the compact disc record has a vastly prolonged playing life since it is free of needle wear, etc.
In adapting the familiar juke box to C.D. record play several serious problems have been encountered among which is that of maintaining the light weight, relatively small C.D. record in proper playing position on the turn table which is generally rotatable at a relatively high speed in the order of 1600 rpm. Early developments accomplished this by centering the record over a projecting centering hub or cone of the turn table and locking the record in position by means of a light weight magnetic disc holder which over engaged the record adjacent its centering aperture and magnetically clamped the same to the the turn table.
In order to accomplish automatic play of a number of compact disc records as in a juke box, a record storage magazine, record transferring means and a turn table along with means for accurately holding the record in playing position are required, all operable in coordinated relationship. Importantly the record disc must be placed accurately on the turn table and a record holder, such as a magnetic disc, must be positioned and accurately aligned with the centering hub of the turn table to effectively carry out the record holding function. Even slight misalignment of the record holding disc can off balance its contact with the record and turn table to produce improper clamping of the record in playing position. If this occurs, the record can slip or move relative to the turn table, particularly at start up of the latter, to produce inaccurate record play. Furthermore, this clamping operation must be carried out play after play, with accuracy and reliability and without the necessity of frequent adjustment of the record holding mechanism. It is to this record holding problem that the present invention is addressed.